1. Field of the Invention
This invention relates generally to a thermal isolation apparatus for biomedical instrumentation, and more particularly relates to thermally isolating a probe of a biomedical thermometer.
2. Description of Related Art
Medical thermometers are useful in the diagnosis of many diseases. Infrared (IR) biomedical thermometers have been adapted for measuring temperature from the auditory canal and the tympanic membrane. Such thermometers typically have an optical path, for example a waveguide, connecting the tip of the probe to a thermal detector located in the body of the thermometer. Temperature stability of this optical path is desirable so that it does not add unknown thermal components and adversely affect the temperature measurement of the patient. Contact of the probe with the ear of the patient may cause a cooling or heating of the ear canal depending upon the relative temperature of the probe, it may also cause heat of the patient to be conducted through the probe and to the waveguide which may result in "hot spots" or temperature variations in the waveguide, and an inaccurate temperature measurement of the patient may result. While it is desirable that physical contact of the probe with the patient not occur, such contact is inevitable. The length of such contact and the point or points of the probe contacting the patient vary with each user of the probe and with the physical configuration of each patient. While probe covers may be used over the thermometer probe to prevent contamination of the probe, these covers typically do not provide substantial thermal isolation by themselves and in fact may, if the probe cover is substantially hotter or colder than the probe or the ear canal, themselves undesirably affect the thermal performance of the probe and the temperature of the ear canal.
It would be desirable for an infrared biomedical probe to include an apparatus for thermally isolating the optical path of the probe from thermal energy which may be transferred to or from the probe by patient contact, by installing a new probe cover, and from other sources of heat or cold with which the probe may come into contact during use. The present invention addresses these needs.